The photographs were all taken by the website author, Bridget Cook. If you would like to make use of them in any way or draw inspiration from them, please acknowledge this website as the source. If you feel they're worth paying for, you might like to make a donation to Friends of the Lake District or Fix the Fells.
I am at best an amateur geologist, and so I hesitate to identify the rocks featured in my photographs. My main aim is to highlight their beauty and to encourage viewers to speculate for themselves what they might be. But for those who like to know what they're looking at, I've listed below the locations of the photographs and my own speculations, along with any guidance from the geology textbooks I used (full details of these books are on the sources page).
I am at best an amateur geologist, and so I hesitate to identify the rocks featured in my photographs. My main aim is to highlight their beauty and to encourage viewers to speculate for themselves what they might be. But for those who like to know what they're looking at, I've listed below the locations of the photographs and my own speculations, along with any guidance from the geology textbooks I used (full details of these books are on the sources page).
Home page
- 1. Grisedale, close to the path just below Grisedale Tarn (NY3512). This reminds me of the type of lava flow that looks like a moving pile of rubble. Or it could be that fragments of surface crust from a liquid lava flow became caught up in the flow. The geology books refer to it as 'brecciated lava', which means that it's made up of broken fragments.
2. Buttermere from Binsey.
3. Hundreds Road, Wansfell (NY3903), definitely Silurian Slate - maybe Brathay Flags?
4. Blindtarn Gill (NY3207). A broken-up lava flow, with burst gas bubbles? or maybe a welded tuff? Or the tablets of stone upon which the story of the Lake District is written.
Iapetus Ocean
- 1. This was taken very near to the junction between the Skiddaw Slates and the Borrowdale Volcanics, alongside Warnscale Beck (NY2013). I think it is Skiddaw Slate, but it could be volcanic.
2. Taken in a disused quarry, now a car park, near Hause Point, Rannerdale (NY1618). Skiddaw Slate.
3. Low tide at Silverdale (SD4575).
4. Skiddaw Slate, on a scree slope below Bannerdale Crags (NY3328).
5. Bakestall and Skiddaw.
6. Skiddaw Slate, car park near Hause Point, Rannerdale (NY1618).
7. Skiddaw Slate, car park near Hause Point, Rannerdale (NY1618).
8. Skiddaw Slate, upper Glenderamackin valley (NY3229).
9. Skiddaw Slate scree, Glenderamackin valley (NY3328).
10. Eycott Volcanic Group, Binsey (NY2235).
11. Eycott Volcanic Group, Binsey (NY2235).
12. Skiddaw Slate, above Ravenstone (NY2329).
13. I think this is a volcanic tuff, but it's so covered in lichen it's difficult to tell. It's near to a waterfall in Red Dell Beck in the Coppermines Valley (SD2898).
Borrowdale Volcano
- 1. Bedded tuff, Levers Water (SD2899).
2. A tuff, very fine ash deposited in water. This was taken in one of the quarries at Low Tilberthwate (NY3000). The colours are caused by minerals leaching out of the hewn rock.
3. Goat’s Water (SD2697). And the rock in the foreground? I don’t know – my guess is a lava or possibly an ignimbrite, but it could be ash… There are some remarkable rocks near to the path that runs alongside Goat’s Water, and it’s well worth lingering to investigate them.
4. This beautiful rock is in Grisedale, on the path up to Grisedale Tarn (NY3512). I think it’s a brecciated lava – broken fragments of solidified lava have been caught up in the flow.
Youth
1. Bedded tuff, Levers Water (SD2899).
2. I think this is a basaltic brecciated lava flow (Moseley, 1983, p.62). Basaltic means that the mineral mix of the lava was relatively low in silica, which means it was more fluid than lava that has a high silica content. It’s at the summit of Hallin Fell (NY4319).
3. This jumble of different sized fragments could have collected around the vent during an explosive eruption. Or it could be the result of an avalanche of loose debris tumbling down the side of the volcano. It’s on a slope littered with boulders above and to the east of Levers Water (SD2899).
4. This boulder is in Grisedale, near the lower footbridge over Grisedale Beck (NY3614). I think it's a lava because of the glassy texture of the unweathered surfaces, and because of the way it cracks into small blocks.
5. I think this is a lava because it is full of gas holes (vesicles). It appears to have engulfed a large fragment of Skiddaw Slate. It could be Shackleton’s “purple breccia” (see no. 9 below), although the base is more red than purple (Cat Ghyll, NY2620).
6. I think this is the “purple breccia” which Shackleton identifies as an “explosion breccia” (1967, pp.26-7), ie broken pieces of rock from an explosion, including “undoubted pieces of Skiddaw Slate … in a fine purple base”. Shackleton identifies the base as “a fine volcanic glass”, ie a lava (see no. 8 above), but it is referred to elsewhere as a volcaniclastic mud, meaning solidified mud containing debris from a volcano (eg Smith, 2010, p.31), and this is what it looks like to me (Cat Ghyll, NY2620).
7. Lava - is this "flow banding"? Summit of High Rigg (NY3022).
8. Or is this "flow banding"? or maybe they both are. This lava contains lots of little gas bubbles (vesicles). Just below the summit of High Rigg (NY3022).
Note that the lavas in photos 4, 6 and 7 belong to the earlier, quieter phase of volcanic eruptions and are therefore probably either basaltic or andesitic. The lavas in photos 8-16 are, I think, from the later phase when the lava had a higher silica content and was much thicker and stickier. They are more likely to be rhyolitic.
9. I think this is a brecciated lava, with mineral veins (quartz?) which are likely to have seeped along cracks at a much later date. This boulder lies beside Red Dell Beck, below Kennel Crag (SD2899).
10-12. More brecciated lava, Grisedale (NY3512).
13. More brecciated lava I think, this time in Far Easedale (NY3209).
14. Not sure, maybe lava, maybe not. Near to the waterfall in Red Dell Beck, Coppermines Valley (SD2898).
15. Brecciated lava, Grisedale (NY3512). Gannon (2009, p.33) has a photo of what looks like the same rock.
16. Blindtarn Gill (NY3207). A brecciated lava which also, I think, shows flow banding. This is the same rock as photo 4 on the Home page.
17. A columnar lava which crosses the path in Grisedale (NY3512).
18. A fine tuff? On the shoreline of Ullswater, below Geordie's Crag (NY4320).
19. A coarse or block tuff, Goat's Water (SD2697).
20. Accretionary lapilli tuff? Blake Rigg, Pike O'Blisco (NY2804) (Gannon, 2009, pp.248-9).
21. Debris from an avalanche or mudflow, Little Round Howe, between Haystacks and Fleetwith Pike (NY2013) (Lynas, 1994, pp.24-6).
22. Andesite lava below (or possibly an intrusion of magma), debris flow/avalanche above, Hogget Gill, Dovedale (NY3811) (Lynas, 1994, pp.43-5).
23. Bedded tuff, upper Dovedale (NY3811).
24. Coarse tuff, Levers Water (SD2899).
25. Bedded tuff, Binka Stone, Thirlmere (NY3113).
26. Bedded tuff, Levers Water (SD2898).
27. Bedded tuff, Binka Stone, Thirlmere (NY3113).
Maturity
1. Bedded tuff, Levers Water (SD2899).
2. I think this is an ignimbrite. Note how the flow lines have been deflected round the larger fragments, which must have remained more or less solid within the flowing debris. The Band (NY2605).
3. Ignimbrite, also referred to as welded tuff, Three Tarns (NY2406) (Lynas, 1994, pp.170-1).
4. Ignimbrite with fiammes, The Band (NY2605).
5. Ignimbrite, Levers Water (SD2799). This streaky texture, known as "eutaxitic" is characteristic of ignimbrite and is caused by the fiammes - the stretched-out glassy blobs of pumice.
6-11. I'm only just beginning to get to grips with ignimbrite and welded tuff, which seem to be different ways of referring to the same thing, but which also seem to vary enormously in appearance, despite being frequently described as "distinctive" in the textbooks. Maybe the dramatic circumstances of their formation gives great scope for variation in the resulting rocks. These are rocks that I think are ignimbrites:
6. Mansey Pike (NY2508).
7. Goat's Water (SD2697).
8. Oxendale (NY2605).
9. Rossett Ghyll (NY2507).
10. Goat's Water (SD2697).
11. Three Tarns (NY2406) (Lynas, 1994, pp.170-1).
12. A peperitic sill - a sheet of lava that pushed its way into a pile of wet ash (NY3005) (Moseley, 1990, pp.145, 148-9).
13. Bedded tuff, Bow Fell (NY2406) (Lynas, 1994, pp.171-3).
14-17. Details from the same outcrop of bedded tuff, showing some of the remarkable structures that form in wet sediment and become petrified (NY2406) (Lynas, 1994, pp.171-3).